During well formation/drilling, operators sometime use liner drill-in techniques to save valuable rig time. Typically, in liner drill-in operations a drill bit is placed on the end of the liner (in a tool string), so that the liner can actually be used to drill the well. This may allow drilling of the hole and placing of the liner in a single operation. And typically, once the liner has been placed downhole, it would then be cemented in place.
While such conventional liner drill-in operations might allow for drilling and liner placement in a single operation, they unfortunately have limitations that make their use impractical in some instances/circumstances. For example, oftentimes packer isolation (in which an open hole packer is placed in the annular space between the liner and the sidewalls of the hole) is required prior to cementing operations, in order to prevent cement losses to the formation below (which might for example, be a low-pressure reservoir). Additionally, rotation of the liner during cementing of the liner in place in the hole may provide higher quality cement coverage in the liner-to-open hole annulus (such that rotation of the liner during cementing can prove beneficial in effectively placing the liner downhole). Unfortunately such rotation of the liner may not be possible in conventional liner drill-in operations, since the packer would prevent free rotation of the liner during cementing. In other words, conventional liner drill-in operations may be unavailable (due to technical and functional limitations) in certain instances, for example when an open hole packer is required to be set against the drilled formation hole, thereby preventing rotation of the liner for improved cementing (since the lower section of the liner would then be coupled to the hole sidewalls).
Disclosed embodiments provide for improved liner drill-in operations, by providing a tool that may be rotationally locked during drilling, but which can be unlocked to allow rotation of the liner above the packer during cementing. These and other improvements are discussed below in more detail.